public class Circle extends Graphic{
    public double getPeri()
    {
        return 2 * _radius * 3.141592;
    }
    public double get_radius() {
        return _radius;
    }

    public  double getAera()
    {
        return _radius * _radius * 3.141592;
    }

    public Circle(double _radius) {
        this._radius = _radius;
    }
    public String getMessage()
    {
        return "圆形，半径是：" + _radius + " 面积是：" + getAera() + " 周长是：" + getPeri();
    }
    private double _radius;
}
